Control systems for monitoring and changing of tap settings on transformers have been utilized with varying levels of success and efficiency. Historically, control systems did not provide for the sophisticated levels of control and monitoring that are highly desirable by means of network connections.
There are relatively large numbers of control cabinets and installations where the control system, while electronic in nature, is not compatible with current networking and communications technology. It is desirable to convert many of the existing control system over to a format that may easily be controlled and monitored remotely over, for example, a network. However, a problem involved with this conversion is that the costs involved with removing the control system and cabinet of the existing system and fully replacing it with an updated electronic system are correspondingly high, both in terms of materials and labor.
For example, control systems for changing of tap settings of a transformer comprise a relatively large amount of input and output signals, both for electronic control and electronic monitoring. These signals however, are generated having a particular format, voltage level, current, etc. To replace the equipment so that a desired signal format can be generated is impractical and extremely costly.
It is also critical that during operation of the tap-changer, that the operation of the tap-changer be monitored so that catastrophic failure is avoided. In relatively large commercial applications, the heat build up that may occur in a tap-changer due to, for example, incomplete switch over or change of a tap setting, can quickly lead to a catastrophic failure of the transformer. This could present a danger to individuals as well as be quite costly both in terms of replacement cost for the transformer and associated equipment, and downtime for customers.
Therefore, an effective monitoring system is critical to the safe functioning of these systems. However, the monitoring systems of many current tap-changers do not lend themselves well to being integrated with a networked control system. The numerous formats of the control and monitoring signals in existing installations further compound the challenge.
Still another challenge facing tap-changing systems is that, even during normal use of the transformer, the various contacts in the tap-changer will wear over time as current is switched by the tap-changer. For example, over time, the contacts for the tap-changer can carbonize, or develop carbon deposits on the surface of the contacts. This is highly disadvantageous because carbon deposits tend to insulate or increase the resistance to the flow of current. With the relatively high voltages typically used for commercial applications, heating and also arcing will occur at these higher resistance locations. The arcing in turn generates very high heat depositing still more carbon on the surface of the contact. If ignored, overheating and arcing due to the poor contact can lead to catastrophic failure of the device may occur.
Accordingly, what is desired is a control system that has the versatility to be integrated and/or retrofitted with existing control signal formats and simultaneously may be integrated with a networked control and monitoring system.
It is further desired to provide a networked control system and method that may effectively be used with existing tap-changing systems to monitor the changing of tap settings and for entering an alarm condition when preset limits are exceeded.
It is still further desired to provide a networked diagnostic control system and method that may be integrated with existing tap-changing system that will substantially minimum or even prevent carbonization of the tap-changer.